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He Yongqiang commented on HIVE-2125: ------------------------------------ It is because the number of reducers is set to -1. In this patch, it is set to zero. Also added a move task as the child task of the merge task. added a conf to control whether to check index or not, and add the job name for the merge job. > alter table concatenate fails and deletes data > ---------------------------------------------- > > Key: HIVE-2125 > URL: https://issues.apache.org/jira/browse/HIVE-2125 > Project: Hive > Issue Type: Bug > Reporter: Joydeep Sen Sarma > Assignee: He Yongqiang > Priority: Critical > Attachments: HIVE-2125.1.patch > > > the number of reducers is not set by this command (unlike other hive > queries). since mapred.reduce.tasks=-1 (to let hive infer this automatically) > - jobtracker fails the job (number of reducers cannot be negative) > hive> alter table ad_imps_2 partition(ds='2009-06-16') concatenate; > alter table ad_imps_2 partition(ds='2009-06-16') concatenate; > Starting Job = job_201103101203_453180, Tracking URL = > http://curium.data.facebook.com:50030/jobdetails.jsp?jobid=job_201103101203_453180 > Kill Command = /mnt/vol/hive/sites/curium/hadoop/bin/../bin/hadoop job > -Dmapred.job.tracker=curium.data.facebook.com:50029 -kill > job_201103101203_453180 > Hadoop job information for null: number of mappers: 0; number of reducers: 0 > 2011-04-22 10:21:24,046 null map = 100%, reduce = 100% > Ended Job = job_201103101203_453180 with errors > Moved to trash: /user/facebook/warehouse/ad_imps_2/_backup.ds=2009-06-16 > after the job fails - the partition is deleted > thankfully it's still in trash -- This message is automatically generated by JIRA. For more information on JIRA, see: http://www.atlassian.com/software/jira